Since one of my families reached the 100 Trophies a few months ago, I've been using Lyssaria's method of trying to get the proposal that I want. After starting a new generation I wait about 1 minute, pause and close the game and save a copy of the game file for that family. So, if I just started a new generation in the 4th game slot I:
1. Using the procedure for backing up game files for
Windows or
Mac to access the files for copying, I make a copy of "Virtual Families4.ldw" and paste it on my computer desktop. I make sure the copy is named "Virtual Families4.ldw" and not "Virtual Families4.ldw copy".
2. I then delete the original game file from the folder and paste in the copy I made, then restart the game. A proposal should come momentarily. If it's not a suitable mate then I reject it, reopen the game folder, toss out the file and repaste the one from my desktop. I do this over and over again.
3. You're not guaranteed the exact proposal you want but sometimes you can get pretty close.